On Thu, Jul 17, 2014 at 10:35 PM, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote: > Clock lines may or may not be shared among different CPUs on a platform. When > clock lines are shared between CPUs, they change DVFS state together. > > Possible configurations: > > 1.) All CPUs share a single clock line. > 2.) All CPUs have independent clock lines. > 3.) CPUs within a group/cluster share clock line but each group/cluster have a > separate line for itself. > > There is no generic way available today to detect which CPUs share clock lines > and so this is an attempt towards that. > > Much of the information is present in the commit and so no point duplicating it > here. > > These are obviously not finalized yet and this is an attempt to initiate a > discussion around this. > > Please share your valuable feedback. > > Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx> > --- > I wasn't sure about the path/name of this file, so please don't blast me on that > :) > > .../devicetree/bindings/cpufreq/cpu_clocks.txt | 159 +++++++++++++++++++++ > 1 file changed, 159 insertions(+) > create mode 100644 Documentation/devicetree/bindings/cpufreq/cpu_clocks.txt > > diff --git a/Documentation/devicetree/bindings/cpufreq/cpu_clocks.txt b/Documentation/devicetree/bindings/cpufreq/cpu_clocks.txt > new file mode 100644 > index 0000000..30ce9ad > --- /dev/null > +++ b/Documentation/devicetree/bindings/cpufreq/cpu_clocks.txt > @@ -0,0 +1,159 @@ > +* Generic CPUFreq clock bindings > + > +Clock lines may or may not be shared among different CPUs on a platform. > + > +Possible configurations: > +1.) All CPUs share a single clock line > +2.) All CPUs have independent clock lines > +3.) CPUs within a group/cluster share clock line but each group/cluster have a > + separate line for itself > + > +Optional Properties: > +- clock-master: This declares cpu as clock master. Other CPUs can either define > + "clock-ganged" or "clock-master" property, but shouldn't be missing both. > + > +- clock-ganged: Should have phandle of a cpu declared as "clock-master". Why complicate it by using two properties? If there is no property, then the CPUs are assumed to be controlled independently. if there is a clock-master = <phandle> property, then that points at the cpu that is the main one controlling clock for the group. There's really no need to label the master -- it will be the only one with incoming links but nothing outgoing. And a master without slaves is an independently controlled cpu so you should be fine in that aspect too. -Olof -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
